The present invention relates to methods and compositions for treating autoimmune diseases, and in particular for treating rheumatoid arthritis.
An xe2x80x9cautoimmunexe2x80x9d disease is understood to be one where the target of the disease is xe2x80x9cselfxe2x80x9d or xe2x80x9cself antigen.xe2x80x9d There are a number of diseases that are believed to involve T cell immunity directed to self antigens, including (but not limited to) multiple sclerosis (MS), Type I diabetes, and rheumatoid arthritis (RA).
RA is a chronic inflammatory disorder characterized by joint pain. The course of the disease is variable, but can be both debilitating and mutilating. According to conservative estimates approximately 50,000,000 individuals are afflicted with RA worldwide. Those individuals are not only subjected to life-long disability and misery, but as current evidence suggests, their life expectancy is compromised as well. Unfortunately, despite considerable investigative efforts there is no cure for RA.
Established treatments of RA are designed to inhibit either final common pathways of inflammation or immunological mediators. Both approaches are non-specific and, therefore, are associated with severe side effects. Corticosteroids have multiple effects on the immune system and other tissues. Their use is complicated by very high incidence of musculoskeletal, metabolic, neurologic and connective tissue side effects, as well as immunosuppression which may lead to life-threatening infections. For this reason, corticosteroids are usually avoided until all other forms of treatment have failed. See generally, R. Million et al., xe2x80x9cLong-Term Study of Management of rheumatoid Arthritis,xe2x80x9d Lancet 1:812 (1984).
Cytotoxic and anti-metabolic drugs, such as methotrexate, azathioprine and cyclophosphamide are non-specifically affecting all rapidly dividing cells and therefore are associated with bone marrow and gastrointestinal toxicity and increased incidence of malignancy. In addition, methotrexate treatment of RA has been reported to induce liver damage and lung disease which may be fatal. See J. A. Engelbrecht et al., xe2x80x9cMethotrexate Pneumonitis After Low-Dose Therapy for Rheumatoid Arthritis,xe2x80x9d Arthritis and Rheumatism 26:1275 (1983) and G. W. Cannon et al., xe2x80x9cAcute Lung Disease Associated With Low-Dose Pulse Methotrexate Therapy In Patients With Rheumatoid Arthritis,xe2x80x9d Arthritis and Rheumatism 26:1269 (1983).
Most nonsteroidal anti-inflammatory drugs (NSAIDs) currently used are designed to non-specifically inhibit prostaglandin synthesis. NSAIDs currently in use modify or diminishxe2x80x94but do not arrestxe2x80x94the inflammatory response. Aspirin remains the most commonly used NSAID. Aspirin toxicity takes many forms, including hypersensitivity reactions, deafness, gastrointestinal and renal toxicity. See generally Simon and Mills, xe2x80x9cNonsteroidal Antiinflammatory Drugs,xe2x80x9d N. Eng. J. Med. 302:1179 (1980).
Gold compounds and penicillamine have also been used in the treatment of RA. They are both associated with high incidence of bone marrow, renal and mucocutaneous toxicity. Gold treatment, in particular, is associated with nephropathy. W. Katz et al., xe2x80x9cProteinuria in Gold-Treated Rheumatoid Arthritis,xe2x80x9d Ann. Int. Med. 101:176 (1984). Penicillamine, while questionably effective, is toxic even at relatively low doses. See W. F. Kean et al., xe2x80x9cThe Toxicity Pattern Of D-Penicillamine Therapy,xe2x80x9d Arthritis and Rheumatism 23:158 (1980). These problems have led to almost complete abandonment of these drugs in RA therapy.
Among the experimental therapies, cyclosporin and anti-TNFxcex1 antibodies show some promise. However, serious renal toxicity and non-specific immunosuppression limit significantly the utility of cyclosporin. Due to its ubiquitous role in many cellular functions, anti-TNF therapy may not be a safe therapeutic strategy for RA. While preliminary results indicate some promise with the anti-TNF approach, development of lupus-like disease has been noticed in some cases.
Thus, current therapies for RA are associated with high incidence of serious side effects. Furthermore, although some medications may offer symptomatic relief, in many cases, they do not significantly modify the progression of joint destruction. What is needed is an effective therapeutic approach with lower toxicity such that the treatment is better tolerated and more appropriate for the treatment of RA.
The present invention relates to methods and compositions for treating and diagnosing autoimmune diseases, and in particular for treating and detecting rheumatoid arthritis. The present invention contemplates a new class of anti-RA drug, namely compounds that inhibit proliferation and induce apoptosis. In one embodiment, the present invention contemplates compounds that are inhibitors of the sphingomyelin signal transduction pathway. For example, the present invention contemplates a method of treating a human, comprising: a) providing: i) a human with symptoms of autoimmune disease, and ii) a preparation comprising at least one inhibitor of the sphingomyelin signal transduction pathway, and b) administering said inhibitor to said human under conditions such that said symptoms are reduced.
It is not intended that the present invention be limited to a particular autoimmune disease. In one embodiment, said human has symptoms of rheumatoid arthritis.
It is not intended that the present invention be limited to a particular route of administration. In one embodiment, said administering comprises intravenous injection. In another embodiment, a mixture of inhibitor and DMSO is applied topically at the joints. In a preferred embodiment, said administering comprises intra-articular injection and said preparation further comprises a local anesthetic. Thus, the present invention specifically contemplates mixtures of inhibitors and anesthetics.
It is not intended that the present invention be limited to a particular inhibitor. As described herein, a variety of pathway inhibitors (specific for different steps in the signal transduction pathway) can be used with success, including but not limited to inhibitors of sphingosine kinase and inhibitors of (ii proteins. In this manner, xe2x80x9cinhibitorsxe2x80x9d are defined functionally as a group (rather than structurally). A variety of sphingosine derivatives are known that are herein contemplated as inhibitors, including but not limited to those described in U.S. Pat. Nos. 5,583,160, 5,627,171, 5,466,716, 5,391,800, 5,137,919, 5,151,360, 5,248,824, 5,260,288 and 5,331,014, all of which are hereby incorporated by reference. Preferred derivatives are methylsphingosine, dimethlylsphingosine and trimethylsphingosine.
While it is not intended that the present invention be limited by the mechanism by which successful treatment and/or protection against autoimmunity is achieved, it is believed that, although the Fas-mediated apoptosis pathway is intrinsically intact in RA lymphocytes, it is reversibly inhibited by sphingomyelin pathway products. This functional inhibition may be sufficient to allow certain subsets of activated lymphocytes to escape apoptosis and accumulate in the joints, thereby contributing to disease pathogenesis. By introducing agents that block the sphingomyelin pathway, the inhibition of lymphocyte apoptosis is reversed and activated lymphocytes are eliminated in a timely fashion.
The present invention also contemplates methods and reagents for diagnostics. While a variety of cells from patients are comtemplated as suitable for the diagnostic assays of the present invention (e.g. synoviocytes), lymphocytes from patients with rheumatoid arthritis are preferred for assays that detect cells displaying impaired Fas-mediated apoptosis. Lymphocytes from such patients express higher levels of antiapoptotic sphingolipid metabolites (such as sphingosine-1-phosphate) and the present invention contemplates testing for the presence of such metabolites by a variety of means (immunoassays, TLC, HPLC, etc.). In one embodiment, the present invention contemplates a method, comprising: a) providing: i) lymphocytes from a human with symptoms of autoimmune disease, and ii) means for detecting at least one metabolite of the sphingomyelin signal transduction pathway: and b) testing said lymphocytes with said means for detecting under conditions such that elevated levels (i.e., elevated relative to lymphocytes from controls) of said metabolite are detected. In one embodiment, said means for detecting is an antibody.
Definitions
The term xe2x80x9capoptosis inducing agentxe2x80x9d refers to any compound or molecule which is capable of causing (directly or indirectly) apoptosis, including but not limited to, inhibitors of the sphingomyelin signal transduction pathway. The present invention contemplates administration of apoptosis inducing agents to autoimmune patients.
The term xe2x80x9csphingomyelin pathway inhibitorxe2x80x9d is used herein to refer to compounds that inhibit downstream events in the sphingomyelin pathway, including but not limited to, inhibitors of sphingosine kinase and Gi proteins inhibitors. Such inhibitors are contemplated to reverse the resistance to apoptosis in RA lymphocytes. Thus, such inhibitors (and apoptosis inducing agents generally) are defined functionally. This function can be readily assessed by using the in vitro assays of the present invention (described below).
The term xe2x80x9csubjectxe2x80x9d refers to both humans and animals.
The term xe2x80x9creceptorsxe2x80x9d refers to structures expressed by cells and which recognize binding molecules (e.g., ligands).
The term xe2x80x9cantagonistxe2x80x9d refers to molecules or compounds which inhibit the action of a xe2x80x9cnativexe2x80x9d or xe2x80x9cnaturalxe2x80x9d compound. Antagonists may or may not be homologous to these natural compounds in respect to conformation, charge or other characteristics. Thus, antagonists may be recognized by the same or different receptors that are recognized by the natural compound. Thus, a kinase inhibitor is a kinase antagonist.
The term xe2x80x9csymptoms of RAxe2x80x9d is intended to encompass any and all symptoms. Where a symptom is said to be xe2x80x9creducedxe2x80x9d it is indicated that the degree of such symptom (such as the degree of joint pain or the amount of inflammatory cells in the joints) is diminished. The present invention is not limited to any particular quantitative level. Most importantly, the present invention is not limited to the complete elimination of symptoms.
The term xe2x80x9cdrugxe2x80x9d as used herein, refers to any medicinal substance used in humans or other animals. Encompassed within this definition arc compound analogs, naturally occurring, synthetic and recombinant pharmaceuticals.